This invention is in the field of electrical and electrochemical devices for storing or harnessing energy. This invention relates generally to management of such devices to reduce the severity of consequences of abnormalities occurring or existing in the devices. Batteries are a prominent example of a type device to which this invention relates.
As battery technology development has progressed, the use of batteries, particularly rechargeable batteries, as a power source has increased substantially. Batteries are used as power sources for a wide array of devices including relatively low-power devices, such as consumer electronics devices, and higher-power devices, such as electric cars. Lithium ion batteries are the most widely used form of rechargeable battery. An Achilles heel of lithium ion batteries is the risk of an electrical short developing inside a lithium ion battery cell and the consequences associated therewith. An electrical short may cause rapid heating of the battery cell. In the matter of seconds, the local temperature at the location of the short may rise to temperatures sufficient to set the battery on fire. This is particularly worrisome in the case of high-capacity lithium ion battery systems, such as those used in electric cars. To reduce the danger associated with electrical shorts and other abnormalities in lithium ion batteries, some battery systems use a battery management system for monitoring the state of charge and/or the state of health of the battery system. Monitoring is typically based upon measurements of properties such as the terminal voltage of the battery system and/or the temperature of the battery system.